B2: Digestive System Review Flashcards
What is the digestive system?
-Group of organs that work together to ingest and break down food and absorb nutrients
Describe physical and chemical breakdown
-Physical involves chewing, churning (stomach) and segmenting (intestines)
-chemical: hydrolysis
What is the role of the mouth?
-Chews and mixes food with saliva
What is the role of the liver?
-Manufactures bile, a substance that facilitates the digestion of fats
What is the role of the gall bladder?
-Stores and concentrates bile which is made from the liver
-releases bile into the small intestine to help digest and absorb fats
What is the role of the large intestine?
-Absorbs water and salt, passes remaining undigested material and some water out of the body
What is the role of the rectum?
-Stores waste prior to elimination
What is the role of esophagus?
-Directs food from the mouth to the stomach
What is the role of the stomach?
-Adds acid, enzyme and fluid: churns, mixes and grinds food into a liquid mass
What is the role of the pancreas?
Manufactures enzymes to digest macromolecules, secretes bicarbonate to neutralize stomach acid that enters the small intestine
What is the role of the small intestine?
-Secrets enzymes that digest macromolecules, absorbs hydrolyzed molecules into bloodstream
What is the role of the salivary glands?
-Produces saliva
-contains enzymes that help begin digestion by breaking down carbohydrates
What is the role of the anus?
-Holds rectum closed, opens to allow elimination
What is pepsin?
-Protien digesting enzyme
What is the epiglottis?
-Flap of tissue that covers the trachea
-ensures food won’t enter the trachea
What is peristalalsis?
-Wave like contracts which push bolus (ball of food made in the mouth) down the esophagus
What is amylase?
-Enzyme that breaks down starch into simple sugars (hydrolysis)
-Produced by salivary gland and the pancreas
What does the esophageal sphincter do?
-relaxes to allow food to enter the stomach then contracts prevents the acidic contents of the stomach to come out
What is chyme?
-Mixture of partially digested food with gastric (digestive) juices in the stomach
-the mixture is the process of the stomach breaking down food
What is in gastric juices?
-Water, mucus, salts and hydrochloride acid
-HCI helps kill pathogens
Why does the stomach not digest it’s own proteins?
-First it secrets little gastric juice until food is present
-then some stomach cells secrete mucus which prevents gastric juices from harming the cells of the stomach barrier (slippery barrier)
-pepsin is produced in a form that remains inactive until hydrochloric acid is present (pep-sinogen)
What does the pyloric sphincter do?
-Controls the movement of chyme into the small intestine
What is absorbed in the stomach?
-Water, salts, anti-inflammatory medicines and alcohol is absorbed in the stomach
What is segmentation?
-Breaking down chyme into small bits
Describe villi
-Long finger like tubes which increase the SA of the small intestine (apx. 10 fold increase)
-Line the inner wall of the small intestine
-each villus is covered in smaller projections called microvilli, which further increase the SA
-increases the small intestines SA make it more efficient for nutrient absorption
What is a lacteal?
-Capillary network that intertwines with lymph vessels
-absorb lipids
What are proteases?
-enzymes that break down proteins into smaller peptides or amino acids
-e.g. trypsin, pepsin, etc
What are carbohydrases?
-Group of enzymes that break down carbohydrates into smaller sugar molecules
-e.g. amylase
What do lipases do?
-Lipid digesting enzymes
-break down fats into smaller molecules
-pancreatic lipase breaks down triglycerides into fatty acids and glycerol
-cholesterol lipase removes a fatty acid from a steroid cholesterol
-a third lipase acts on phospholipids and breaks them down into glycerol and fatty acids
